Achromycin Oral Uses Tetracycline is used to treat a wide variety of infections, including acne. It is an antibiotic that works by stopping the growth of bacteria. This antibiotic treats only bacterial infections. It will not work for viral infections (e.g., common cold, flu). Unnecessary use or overuse of any antibiotic can lead to its decreased effectiveness. How to use Achromycin Oral Tetracycline works best when taken on an empty stomach 1 hour before or 2 hours after meals. If stomach upset occurs, ask your doctor if you can take this medication with food. Take each dose with a full glass of water (8 ounces or 240 milliliters) unless your doctor directs you otherwise. Do not lie down for 30 minutes after taking this medication. For this reason, do not take it right before bedtime. Take this medication 2-3 hours before or after taking any products containing magnesium, aluminum, or calcium. Some examples include antacids, quinapril, certain forms of didanosine (chewable/dispersible buffered tablets or pediatric oral solution), vitamins/minerals, and sucralfate. Follow the same instructions with dairy products (e.g., milk, yogurt), calcium-enriched juice, bismuth subsalicylate, iron, and zinc. These products bind with tetracycline, preventing its full absorption. Dosage is based on your medical condition and response to therapy. For use in children older than 8 years of age, the dosage is also based on weight. Antibiotics work best when the amount of medicine in your body is kept at a constant level. Therefore, take this drug at evenly spaced intervals. Continue to take this medication until the full-prescribed amount is finished even if symptoms disappear after a few days. Stopping the medication too early may allow bacteria to continue to grow, which may result in a relapse of the infection. Inform your doctor if your condition persists or worsens.